I have been speaking to Vortex Antenna Systems regarding a possible Delta Loop antenna for 10, 6 and 4 Metres. They have modelled an antenna which is 2 elements on 10m and 6m, 4 elements on 4m. The minimum figures are as follows:
- 10m – 7.09 dbi and 21db front to back.
- 6m – 8.46 dbi and 25db front to back.
- 4m – 9.1 4dbi and nearly 30 db front to back.
- Boom length is around 3.8m.
Check out their website at http://www.vortexantennas.co.uk/shop/triband-delta-10m2-6m2-4m4/ for further info.